It is pure and does not mix other programming paradigms into the language. This forces you to learn functional programming in its most pure form. This avoids you falling back on old habits and learn an entirely new way to program.

Haskell's referential transparency, consistency, mathematics-oriented culture, and heavy amount of abstraction encourage problem solving at a very high level. The fact that this is all built upon little other than function application means that not only is the thought process, but even concre...

Haskell lends itself well to powerful abstractions - the result is that even basic, commonly used libraries, while easy to use, are implemened using a vocabularly that requires a lot of backround in abstract mathematics to understand. Even a concept as simple as "combine A and B" is ofte...

Haskell's language extensions, while making the language incredibly flexible for experienced users, makes a lot of code incredibly unfamiliar for beginners. Some pragmas, like NoMonomorphismRestriction, have effects that seem completely transparent in code, leading beginners to wonder why it...

Haskell allows users to define their own infix operators, even with their own precedence. The result is that some code is filled with foreign looking operators that are assumed to be special-case syntax. Even for programmers who know they're just functions, operators that change infix preceden...

Scala supports both Functional and Object Oriented styles of programming. Beginners can learn both paradigms without having to learn a new language, and experts can switch between the two according to what best suits their needs at the time.

Scala is an industrial language. It brings functional programming to the JVM, but not with a "start small and grow the language" perspective, but rather a very powerful language for professional programmers.

Some design choices could have been a little more appealing, for example: using "do...end" comes natural in Ruby for blocks but Elixir uses them for everything and it looks pretty weird: Enum.map [1, 2, 3], fn(x) -> x * 2 end or receive do {:hello, msg} -> msg {:world,...

Python's popularity and beginner friendliness has led to a wealth of tutorials and example code on the internet. This means that when beginners have questions, they're very likely to be able to find an answer on their own just by searching. This is an advantage over some languages that are...

On top of the wealth of tutorials and documentation, and the fact that it ships with a sizeable standard library, Python also ships with both an IDE (Integrated Development Environment: A graphical environment for editing running and debugging your code); as well as a text-based live interpreter....

Python's syntax is very clear and readable, making it excellent for beginners. The lack of extra characters like semicolons and curly braces reduces distractions, letting beginners focus on the meaning of the code. Significant whitespace also means that all code is properly and consistently ind...

A large subset of the Python community still uses / relies upon Python 2, which is considered a legacy implementation by the Python authors. Some libraries still have varying degrees of support depending on which version of Python you use. There are syntactical differences between the versions.

You have generics, you have interfaces, you have inheritance, you have a lot of things at your disposal but you don't have Type Clases. They can be emulated using some clever constructs but there's nothing like having the real thing.

Since Kotlin is made by Jetbrains (the developers of IntelliJ IDEA) so it stands to reason that the IntelliJ support for Kotlin is also great. Besides that, Kotlin also works well with existing Java tools such as Eclipse, Maven, Gradle, Android Studio, etc...

Kotlin runs on the JVM and Java interoperability has been one of the main objectives since the language was born. It runs everywhere Java does; web servers, mobile devices (Android), and desktop applications. It also works with all the major tools in the Java ecosystem like Eclipse, IntelliJ, Mave...

Since Kotlin does not enforce any particular paradigms and is not purely functional, it can be pretty easy to fall back to imperative programming habits if a programmer comes from an imperative background.

Goroutines are "lightweight threads" that runs on OS threads. They provide a simple way for concurrent operations — prepending a function with go will execute it concurrently. It utilizes channels for communication between goroutines which aids to prevent races and makes synchronizing exe...

Go has a solid team of engineers working on it (some of the best networking engineers in the world are working on Go). Up until now, the great engineering of the language has compensated for its lack of power.

Go is famously regarded as very simple. However, this simplicity becomes problematic in time. Programmers who use Go find themselves over and over again writing the same thing from a very low point of view. Domains not already served by libraries that are easy to glue are very difficult to get int...

Go was designed for large team projects where many contributors may be incompetent. That Go can still get things done under these conditions is a testament to its utility in this niche. Go's infamously weak abstraction power is thus a feature, not a bug, meant to prevent your teammates from doi...

A standard step of even installing Go is modifying your path -- a person who's encountering their first language might not even understand. It's hard to escape using Go without familiarity with using build tools, managing and organizing project directories, etc. It's not as simple as Py...

Since Rust is statically typed, you can catch multiple errors during compile time. This is extremely helpful with debugging, especially compared with dynamically typed languages that may fail silently during runtime.

Unique ownership system guarantees a mutable data to be owned and mutated by only one thread at a time, so there's no data race, and this guarantee is checked at compile time statically. Which means easy multi-threading. Of course, immutable data can be shared among multiple threads freely.

Because it's still a relatively new language, Rust does not enjoy a following as large as other languages/environments. Rust development has also been rather volatile for a long time during the beginning of the development of the language adding to this issue. Because of the small community,...

If you run a web browser you already have JavaScript installed and can get started right away. Modern browsers such as Chrome also have very powerful programming consoles built into them. Aside from the browser console, you can also use online Javascript playgrounds such as JS Bin and JS Fiddle....

If you are looking to create web projects, you will have to learn Javascript in order to develop the client side code. If you learn the foundations of programming in JavaScript you can reapply that education later in building web applications.

With Node.js, it is now possible to run JavaScript as a web server. This would allow you to be able to create server based applications sooner than would if you had to learn a separate programming language as well for server side code. As JavaScript is the only language supported by web browsers...

JavaScript looks for every possible way to treat the code you write as runnable and is very reluctant to point out likely errors. For example, you have call a function with too many arguments, the extra arguments are simply discarded.

If you forget a var or new, you can clobber the global scope. For tiny scripts (JavaScript's original use case) globals are great, but for larger applications globals are generally regarded as a Bad Thing. This is because changes to one small part of a program can randomly break things anywhere...

Fault tolerance means that a system has the property to continue operating even though one or more components have failed. For Erlang systems, this means that the system is kept running even if for example a user has to drop a phone call rather than forcing everyone else to do so. In order to ach...

In a real-time system it may not be possible to stop the system in order to implement code upgrades. For these cases Erlang gives you dynamic code upgrade support for free when using OTP. The mechanism is very easy to understand and works as follows: Start the app Edit the code Recompi...

Erlang's syntax may feel very strange to 99% of programmers who have never used it. This is because it does not share any similarities or common syntax definitions that are found in all the other languages that are used today.

Erlang is not really a general purpose language. It has a very special and well-defined niche where it towers above everything else. It's specialized in scalability and in distributed applications. Which is not necessarily a bad thing per se, but it still lacks and falls behind other languages...

Out of the box Julia has a very good Read-Eval-Print-Loop, which both completes functions and types, as well as completion based on history of previous statements. It integrates well with the shell and has an excellent online help system.

Julia code is easy to read and avoid a lot of unnecessary special symbols and fluff. It uses newline to end statements and "end" to end blocks so there is no need for lots of semicolons and curly braces. It is regular in that unless it is a variable assignment, function name always comes...

Julia was released in 2012. Due to its short existence, there is a limited amount of support for the language. Very few libraries exist as of yet, and the community is still quite small (though growing quickly).

C# runs on top of the .NET framework, which provides many libraries containing classes used for common tasks such as connecting to the Internet, displaying a window or editing files. Unlike many other languages, you don't have to pick between a handful of libraries for every small task you want...

Where other languages invoke the feeling of being a product of organic growth over time, C# just feels like an incredibly well-designed language where everything has its purpose and almost nothing is non-essential.

On Windows, Visual Studio is the recommended C# IDE. It provides a very flexible GUI that you can rearrange the way you want and many useful features such as refactorings (rename a variable, extract some code into a method, ...) and code formatting (you can pick exactly how you want the code to be...

Most people learn and depend on VisualStudio to write C#. The result is people learn how to use an IDE and not the concepts or fundamentals of good programming. This isn't necessarily a knock on the language itself, but it is frustratingly difficult to do things in C# when not using VS.

Scheme syntax is extremely regular and easy to pick up. A formal specification of the syntax fits onto just a few pages; it can be introduced informally in a paragraph or two. Students are not distracted by remembering how to write if statements or loops or even operator precedence because every s...

Scheme has far less built into the language itself, helping students see that things like OOP are not magical: they are just patterns for organizing code. Everything in Scheme is built up from a very small set of primitives which compose in a natural and intuitive fashion. Having a language that d...

Scheme is an IEEE standard, not an implementation. Unfortunately, the standard is too minimal and practical implementations have diverged--they had to expand on the standard to get anything done, but did so in incompatible ways. The later de facto standard R6RS tried to correct this, but lost Sch...

LISP-like languages are very different from mainstream languages (such as C/C++/Java/JavaScript/Python/you-name-it) - both in semantics and syntax. This, in turn, severely limits uses of whatever-learned-with-Scheme, for real-world use.

Ruby has a very clean syntax that makes code easier to both read and write than more traditional Object Oriented languages, such as Java. For beginning programmers, this means the focus is on the meaning of the program, where it should be, rather than trying to figure out the meaning of obscure cha...

Ruby has a large ecosystem of tools and libraries for just about every use. Such as ORMs (Active Record, DatabMapper), Web Application Frameworks(Rails, Sinatra, Volt), Virtualization Orchestration(docker-api, drelict), CLI tools(Thor, Commando), GUI Frameworks(Shoes, FXRuby) and the list goes on.

Ruby is one of the most popular languages for developing web sites. As a result, there's an abundant amount of documentation, sample code, and libraries available for learning the language and getting your project up and running. The most popular features are just 'gem install' away. A...

If you're looking to host, generate, manipulate or secure a website, Ruby is your language. There's also some great support here for infrastructure as code work via Chef. However, it just doesn't have the depth and breadth that Python does. Things like native UI development, high per...

The ability for libraries to open classes and augment them leads to confusion for new developers since it is not clear who injected the functionality into some standard class. In other words, if two modules decide to modify the same function on the same class can introduce a number of issues. Main...

Because Java is statically typed, integrated development environments (IDEs) for Java can provide a lot more feedback on errors you will encounter. Java IDEs can give you specific errors in the location where they occur without having to run the code every time. This makes is faster to debug and le...

Most Java code follows very standardized coding styles. This means that when you're starting out, there are fewer questions about how you should implement something as the programming styles and patterns are well established and consistent. This consistent style means that it's often easier...

Java is one of the most popular languages in industry, consistently ranking either first, or occasionally second (behind C or Javascript) in terms of usage. Polls (see sources below) show it to be consistently in high demand, particularly as measured by job board postings. This makes Java a great t...

A Hello world needs package, class, static method and the actual printf. Reading a line from input requires instatiating 5 objects in the right order. Exceptions are everywhere, particularly since all values are nullable. Java has a getter/setter culture, but without native syntax suppo...

Some features in Java can be quite confusing for beginners. Encapsulation is needlessly obfuscated with a confusing access control model. As an example, the "protected" keyword not only grants access to child classes, but to the entire package. Since small programs are written as one pa...

Java evolves very slowly - lambda expressions weren't available until Java 8 (which is not available on Android), and despite getters/setters being a long-time convention, the language still doesn't have native accessor syntax (a la C#'s properties). It's unlikely newer, popular fea...

Racket is based on Scheme (LISP Family) and is very similar to Clojure. So there are a ton of (). The reason it is easier to learn is that it is not trying to be "Pure" if there is even such a thing in terms of Functional Programming. The great thing about Racket is it has everything incl...

Realm of Racket teaches the big-bang approach for managing world state. It does so by walking the reader through the development of small games. There are few guidebooks that are as useful and entertaining.

As Elm was designed as a front-end langauge, it has out of the box support for things like DOM-element creation, letting programmers focus on their application logic, rather than implementation details specific to the web.

One of the best features of Lua is its very well designed C API. This is very useful if you have an existing C library you need to integrate with Lua or quickly get a Lua script running on the C side of the game. Finally Lua plays so nice with C that if you need to optimise for speed you can re-w...

Lua can be built on any platform with a ANSI C compiler. Other than that, Lua is extremely small. For example, the tarball for Lua 5.2.1 is only 245K compressed and 960K uncompressed (including documentation). When built on Linux, the Lua interpreter built with the standard libraries takes 182K...

When writing a function, if a programmer forgets to declare a variable, that variable will be declared at global scope. The code will seem to run fine at first, but if another function uses a variable with the same name, but fails to declare it, it will create subtle, incredibly difficult to find b...

Lua features a prototye-based inheritance model. While this is also used by Javascript, it's not used by many other mainstream languages, and so some of the concepts learned while learning Lua won't be very applicable to other languages. Another thing that makes Lua different from other pr...

Lua is so small mainly due to many of the components not being included in the core package. A lot of people need the functionality provided by the Lua module management system LuaRocks and libraries such as Penlight.

One big advantage over pure javascript, (or some other languages listed here) is that Haxe will pick up a whole range of errors when you compile, saving you the pain of having to try and debug them later. This includes everything from syntax errors ("Unexpected ;") to type errors ("...